CMM "interfering" with PS color picker ?...
CMM "interfering" with PS color picker ?...
- Subject: CMM "interfering" with PS color picker ?...
- From: Terry Wyse <email@hidden>
- Date: Tue, 30 Jan 2001 12:59:53 -0500
Ran into something a bit disconcerting in PS6 recently.
Settings:
RGB: Adobe98
CMYK: custom "PressCMYK" ICC profile that I created using ProfileMaker 3.1.
CMM: Heidelberg or Adobe.
Select the "default" Black/White foreground/background option. Choose the
White and view the Color Picker values.
RGB = 255/255/255
Lab = 100/0/0
*CMYK = 1/1/2/0* (What's with that?)
If I manually set CMYK = 0/0/0/0, the RGB then = 253/254/254
I guess I'm confused why RGB=255/255/255 doesn't = 0% CMYK and, in fact that
0% CMYK, when set manually, = something LESS than RGB=255/255/255.
If I change to the Adobe CMM (I was using Heidelberg in the example above),
I get different values but still not a pure white in CMYK.
Oddly enough, if I try the same thing in PS5.5, I get the same results using
the Heidelberg CMM but I *do* get 0%CMYK with the Adobe engine. Adobe engine
changed slightly in PS6? Also, a change in rendering intent (relcol vs.
percept.) made no difference.
I also did some checking of the "Black" (RGB=0/0/0) and noticed a couple of
things:
1) changing CMMs results in a slightly different CMYK balance. For roughly
the same total ink, the Heidelberg CMM tended towards less K and more CMY.
The opposite was true of the Adobe CMM. The Adobe CMM gave me closer to what
I had spec'd in the separation setup for the K limit in ProfileMaker.
2) Although neither CMM gave me the Total Ink I had set in the separation
setup (naturally may be a function of the total ink I was "requesting" vs.
the amount of UCR/GCR I had spec'd), the Adobe CMM gave me on average about
3-5% more total ink.
I don't suspect that there's anything "wrong" with my profiles as they have
been giving us excellent results in all cases.
Inquiring minds need to know...
Terry
_____________________________
Terence (Terry) Wyse
PrePress Specialist
All Systems Integration, Inc.
781.935.3322 voice
781.935.6622 fax
http://www.allsystems.com
email@hidden
_____________________________